162 William Libbey-Gulf Stream and Labrador Current.
series of meteorologic observations ; and serial observations were
made on the temperature of the water at each of the several
stations.
In the serial temperature work the thermometers were fastened
to a wire cable of 19 strands of number 24 crucible steel music
wire, with a breaking strain of 1,500 pounds. The interval be
tween the instruments varied as the depth increased. They were
placed closer together where the changes were quickest-i. e.,
near the surface-and where the temperatures became more
regular they were placed further apart. We only adopted a
regular system for the distribution of the thermometers along
the cable after having examined the whole area to be studied
from north to south along several lines and were sure that all
the facts were covered by the system.
The area was studied by running out a series of lines 10 miles
apart, along which at intervals of 10 miles the stations were made.
These lines were repeated as often as possible, and temperature
profile curves were plotted along these lines, based on the observa
tions made at the stations. On most of these temperature pro
files we have given the curves of 70°, 60° and 500 as being the
most important.
The 500 curve has been an interesting one from the beginning,
as it was the means of showing us that there were two sets of
conditions under which the two measurably distinct bodies of
water came in contact.
It will be convenient to speak of these two portions of the
main current of the Gulf stream separately. I shall therefore
speak of the upper portion first.
I. Upper Portion.
The boundary between the cold and the warm currents of the
surface is very seldom a straight line, perpendicular to the sur
face. It marks the position of the resultant of all the forces at
work. Of course the general position of the boundary will be
determined by the velocities of the two bodies and the direction
of their currents when they come in contact.
If we leave out of consideration the wind as an effective agent
in the production and directing of the oceanic currents, we find
that it becomes a most potent factor in the changes which are